When designing step movement mechanism used in a variety of products, designer frequently meets difficulties to achieve reliable step movement with reliability with a small number of parts. Mechanism designers must achieve step movement when they want to stop some parts in several positions with accurate positioning and holding it in that position even when external shocks or movements disturb the mechanical system.
Normally, a step movement mechanism has to provide several essential features such as accurate stop position control, locking the parts in stop positions, accurate distance between steps (stop positions), easiness to control, allowing tolerance of positioning sensors while still being able to keep accurate stop position and produce less noise and etc. However, in order to achieve accurate step movement and realize accurate stop position control, the conventional step movement mechanism usually has a complicated structure with a large number of parts, resulting in a reduction of reliability and an increase of the manufacturing cost.